"""
Footnotes Extension for Python-Markdown
=======================================
Adds footnote handling to Python-Markdown.
See <https://pythonhosted.org/Markdown/extensions/footnotes.html>
for documentation.
Copyright The Python Markdown Project
License: [BSD](http://www.opensource.org/licenses/bsd-license.php)
"""
from __future__ import absolute_import
from __future__ import unicode_literals
from . import Extension
from ..preprocessors import Preprocessor
from ..inlinepatterns import Pattern
from ..treeprocessors import Treeprocessor
from ..postprocessors import Postprocessor
from .. import util
from ..odict import OrderedDict
import re
import copy
FN_BACKLINK_TEXT = util.STX + "zz1337820767766393qq" + util.ETX
NBSP_PLACEHOLDER = util.STX + "qq3936677670287331zz" + util.ETX
DEF_RE = re.compile(r'[ ]{0,3}\[\^([^\]]*)\]:\s*(.*)')
TABBED_RE = re.compile(r'((\t)|( ))(.*)')
RE_REF_ID = re.compile(r'(fnref)(\d+)')
class FootnoteExtension(Extension):
""" Footnote Extension. """
def __init__(self, *args, **kwargs):
""" Setup configs. """
self.config = {
'PLACE_MARKER':
["///Footnotes Go Here///",
"The text string that marks where the footnotes go"],
'UNIQUE_IDS':
[False,
"Avoid name collisions across "
"multiple calls to reset()."],
"BACKLINK_TEXT":
["↩",
"The text string that links from the footnote "
"to the reader's place."]
}
super(FootnoteExtension, self).__init__(*args, **kwargs)
# In multiple invocations, emit links that don't get tangled.
self.unique_prefix = 0
self.found_refs = {}
self.used_refs = set()
self.reset()
def extendMarkdown(self, md, md_globals):
""" Add pieces to Markdown. """
md.registerExtension(self)
self.parser = md.parser
self.md = md
# Insert a preprocessor before ReferencePreprocessor
md.preprocessors.add(
"footnote", FootnotePreprocessor(self), "<reference"
)
# Insert an inline pattern before ImageReferencePattern
FOOTNOTE_RE = r'\[\^([^\]]*)\]' # blah blah [^1] blah
md.inlinePatterns.add(
"footnote", FootnotePattern(FOOTNOTE_RE, self), "<reference"
)
# Insert a tree-processor that would actually add the footnote div
# This must be before all other treeprocessors (i.e., inline and
# codehilite) so they can run on the the contents of the div.
md.treeprocessors.add(
"footnote", FootnoteTreeprocessor(self), "_begin"
)
# Insert a tree-processor that will run after inline is done.
# In this tree-processor we want to check our duplicate footnote tracker
# And add additional backrefs to the footnote pointing back to the
# duplicated references.
md.treeprocessors.add(
"footnote-duplicate", FootnotePostTreeprocessor(self), '>inline'
)
# Insert a postprocessor after amp_substitute oricessor
md.postprocessors.add(
"footnote", FootnotePostprocessor(self), ">amp_substitute"
)
def reset(self):
""" Clear footnotes on reset, and prepare for distinct document. """
self.footnotes = OrderedDict()
self.unique_prefix += 1
self.found_refs = {}
self.used_refs = set()
def unique_ref(self, reference, found=False):
""" Get a unique reference if there are duplicates. """
if not found:
return reference
original_ref = reference
while reference in self.used_refs:
ref, rest = reference.split(self.get_separator(), 1)
m = RE_REF_ID.match(ref)
if m:
reference = '%s%d%s%s' % (m.group(1), int(m.group(2))+1, self.get_separator(), rest)
else:
reference = '%s%d%s%s' % (ref, 2, self.get_separator(), rest)
self.used_refs.add(reference)
if original_ref in self.found_refs:
self.found_refs[original_ref] += 1
else:
self.found_refs[original_ref] = 1
return reference
def findFootnotesPlaceholder(self, root):
""" Return ElementTree Element that contains Footnote placeholder. """
def finder(element):
for child in element:
if child.text:
if child.text.find(self.getConfig("PLACE_MARKER")) > -1:
return child, element, True
if child.tail:
if child.tail.find(self.getConfig("PLACE_MARKER")) > -1:
return child, element, False
child_res = finder(child)
if child_res is not None:
return child_res
return None
res = finder(root)
return res
def setFootnote(self, id, text):
""" Store a footnote for later retrieval. """
self.footnotes[id] = text
def get_separator(self):
if self.md.output_format in ['html5', 'xhtml5']:
return '-'
return ':'
def makeFootnoteId(self, id):
""" Return footnote link id. """
if self.getConfig("UNIQUE_IDS"):
return 'fn%s%d-%s' % (self.get_separator(), self.unique_prefix, id)
else:
return 'fn%s%s' % (self.get_separator(), id)
def makeFootnoteRefId(self, id, found=False):
""" Return footnote back-link id. """
if self.getConfig("UNIQUE_IDS"):
return self.unique_ref('fnref%s%d-%s' % (self.get_separator(), self.unique_prefix, id), found)
else:
return self.unique_ref('fnref%s%s' % (self.get_separator(), id), found)
def makeFootnotesDiv(self, root):
""" Return div of footnotes as et Element. """
if not list(self.footnotes.keys()):
return None
div = util.etree.Element("div")
div.set('class', 'footnote')
util.etree.SubElement(div, "hr")
ol = util.etree.SubElement(div, "ol")
surrogate_parent = util.etree.Element("div")
for id in self.footnotes.keys():
li = util.etree.SubElement(ol, "li")
li.set("id", self.makeFootnoteId(id))
# Parse footnote with surrogate parent as li cannot be used.
# List block handlers have special logic to deal with li.
# When we are done parsing, we will copy everything over to li.
self.parser.parseChunk(surrogate_parent, self.footnotes[id])
for el in list(surrogate_parent):
li.append(el)
surrogate_parent.remove(el)
backlink = util.etree.Element("a")
backlink.set("href", "#" + self.makeFootnoteRefId(id))
if self.md.output_format not in ['html5', 'xhtml5']:
backlink.set("rev", "footnote") # Invalid in HTML5
backlink.set("class", "footnote-backref")
backlink.set(
"title",
"Jump back to footnote %d in the text" %
(self.footnotes.index(id)+1)
)
backlink.text = FN_BACKLINK_TEXT
if li.getchildren():
node = li[-1]
if node.tag == "p":
node.text = node.text + NBSP_PLACEHOLDER
node.append(backlink)
else:
p = util.etree.SubElement(li, "p")
p.append(backlink)
return div
class FootnotePreprocessor(Preprocessor):
""" Find all footnote references and store for later use. """
def __init__(self, footnotes):
self.footnotes = footnotes
def run(self, lines):
"""
Loop through lines and find, set, and remove footnote definitions.
Keywords:
* lines: A list of lines of text
Return: A list of lines of text with footnote definitions removed.
"""
newlines = []
i = 0
while True:
m = DEF_RE.match(lines[i])
if m:
fn, _i = self.detectTabbed(lines[i+1:])
fn.insert(0, m.group(2))
i += _i-1 # skip past footnote
self.footnotes.setFootnote(m.group(1), "\n".join(fn))
else:
newlines.append(lines[i])
if len(lines) > i+1:
i += 1
else:
break
return newlines
def detectTabbed(self, lines):
""" Find indented text and remove indent before further proccesing.
Keyword arguments:
* lines: an array of strings
Returns: a list of post processed items and the index of last line.
"""
items = []
blank_line = False # have we encountered a blank line yet?
i = 0 # to keep track of where we are
def detab(line):
match = TABBED_RE.match(line)
if match:
return match.group(4)
for line in lines:
if line.strip(): # Non-blank line
detabbed_line = detab(line)
if detabbed_line:
items.append(detabbed_line)
i += 1
continue
elif not blank_line and not DEF_RE.match(line):
# not tabbed but still part of first par.
items.append(line)
i += 1
continue
else:
return items, i+1
else: # Blank line: _maybe_ we are done.
blank_line = True
i += 1 # advance
# Find the next non-blank line
for j in range(i, len(lines)):
if lines[j].strip():
next_line = lines[j]
break
else:
break # There is no more text; we are done.
# Check if the next non-blank line is tabbed
if detab(next_line): # Yes, more work to do.
items.append("")
continue
else:
break # No, we are done.
else:
i += 1
return items, i
class FootnotePattern(Pattern):
""" InlinePattern for footnote markers in a document's body text. """
def __init__(self, pattern, footnotes):
super(FootnotePattern, self).__init__(pattern)
self.footnotes = footnotes
def handleMatch(self, m):
id = m.group(2)
if id in self.footnotes.footnotes.keys():
sup = util.etree.Element("sup")
a = util.etree.SubElement(sup, "a")
sup.set('id', self.footnotes.makeFootnoteRefId(id, found=True))
a.set('href', '#' + self.footnotes.makeFootnoteId(id))
if self.footnotes.md.output_format not in ['html5', 'xhtml5']:
a.set('rel', 'footnote') # invalid in HTML5
a.set('class', 'footnote-ref')
a.text = util.text_type(self.footnotes.footnotes.index(id) + 1)
return sup
else:
return None
class FootnotePostTreeprocessor(Treeprocessor):
""" Ammend footnote div with duplicates. """
def __init__(self, footnotes):
self.footnotes = footnotes
def add_duplicates(self, li, duplicates):
""" Adjust current li and add the duplicates: fnref2, fnref3, etc. """
for link in li.iter('a'):
# Find the link that needs to be duplicated.
if link.attrib.get('class', '') == 'footnote-backref':
ref, rest = link.attrib['href'].split(self.footnotes.get_separator(), 1)
# Duplicate link the number of times we need to
# and point the to the appropriate references.
links = []
for index in range(2, duplicates + 1):
sib_link = copy.deepcopy(link)
sib_link.attrib['href'] = '%s%d%s%s' % (ref, index, self.footnotes.get_separator(), rest)
links.append(sib_link)
self.offset += 1
# Add all the new duplicate links.
el = list(li)[-1]
for l in links:
el.append(l)
break
def get_num_duplicates(self, li):
""" Get the number of duplicate refs of the footnote. """
fn, rest = li.attrib.get('id', '').split(self.footnotes.get_separator(), 1)
link_id = '%sref%s%s' % (fn, self.footnotes.get_separator(), rest)
return self.footnotes.found_refs.get(link_id, 0)
def handle_duplicates(self, parent):
""" Find duplicate footnotes and format and add the duplicates. """
for li in list(parent):
# Check number of duplicates footnotes and insert
# additional links if needed.
count = self.get_num_duplicates(li)
if count > 1:
self.add_duplicates(li, count)
def run(self, root):
""" Crawl the footnote div and add missing duplicate footnotes. """
self.offset = 0
for div in root.iter('div'):
if div.attrib.get('class', '') == 'footnote':
# Footnotes shoul be under the first orderd list under
# the footnote div. So once we find it, quit.
for ol in div.iter('ol'):
self.handle_duplicates(ol)
break
class FootnoteTreeprocessor(Treeprocessor):
""" Build and append footnote div to end of document. """
def __init__(self, footnotes):
self.footnotes = footnotes
def run(self, root):
footnotesDiv = self.footnotes.makeFootnotesDiv(root)
if footnotesDiv is not None:
result = self.footnotes.findFootnotesPlaceholder(root)
if result:
child, parent, isText = result
ind = parent.getchildren().index(child)
if isText:
parent.remove(child)
parent.insert(ind, footnotesDiv)
else:
parent.insert(ind + 1, footnotesDiv)
child.tail = None
else:
root.append(footnotesDiv)
class FootnotePostprocessor(Postprocessor):
""" Replace placeholders with html entities. """
def __init__(self, footnotes):
self.footnotes = footnotes
def run(self, text):
text = text.replace(
FN_BACKLINK_TEXT, self.footnotes.getConfig("BACKLINK_TEXT")
)
return text.replace(NBSP_PLACEHOLDER, " ")
def makeExtension(*args, **kwargs):
""" Return an instance of the FootnoteExtension """
return FootnoteExtension(*args, **kwargs)